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Ubiquitin‐conjugating enzymes UBC4 and UBC5 mediate selective degradation of short‐lived and abnormal proteins.
Author(s) -
Seufert W.,
Jentsch S.
Publication year - 1990
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1990.tb08141.x
Subject(s) - ubiquitin conjugating enzyme , biology , ubiquitin , saccharomyces cerevisiae , enzyme , ubiquitin ligase , gene , yeast , biochemistry , genetics , microbiology and biotechnology
Ubiquitin‐conjugating enzymes catalyse the covalent attachment of ubiquitin to target proteins. Members of this enzyme family are involved in strikingly diverse cellular functions: UBC2 (RAD6) is central to DNA repair, UBC3 (CDC34) is involved in cell cycle control. We have cloned the genes for two novel ubiquitin‐conjugating enzymes, UBC4 and UBC5, from the yeast Saccharomyces cerevisiae. These enzymes mediate selective degradation of short‐lived and abnormal proteins. UBC4 and UBC5 are closely related in sequence and complementing in function. Expression of UBC4 and UBC5 genes is heat inducible. UBC4 and UBC5 enzymes generate high mol. wt ubiquitin‐protein conjugates in vivo consistent with previous studies which suggested that attachment of multiple ubiquitin molecules to proteolytic substrates is required for their selective degradation. UBC4 and UBC5 enzymes comprise a major part of total ubiquitin‐conjugation activity in stressed cells. Turnover of short‐lived proteins and canavanyl‐peptides but not of long‐lived proteins is markedly reduced in ubc4ubc5 mutants. Loss of UBC4 and UBC5 activity impairs cell growth, leads to inviability at elevated temperatures or in the presence of an amino acid analog, and induces the stress response.